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(No Model.) I 2 Sheets--Sheet 1. S. H. BARTLETT & H. E. WAITE.

TRANSMITTER FOR TELEPHONES.

No. 252,714. Patented Jan. 24,1882.

N. PETERS. Pham-Lnhugmaher. Wmhingtm D. c

' 2 Sheets-Sheet 2. S. H. BARTLETT & H. E. WAITE.

TRANSMITTER FOR TELEPHONES.

No. 252,714. Patented Jan. 24,1882.

(No Model.)

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UNITED STATES PATENT E icE.

SAMUEL H. BARTLETT AND HENRY E. WAITE, OF NEW YORK, N. Y., ASSIGN OHS TO CHARLES F. LIVERMORE, OF SAME PLACE.

TRANSMITTER FOR :I'ELEPHONES.

SPECIFICATION forming part of Letters Patent No. 252,714, dated January 24, 1882.

Application filed November 523, 1881.

To all whom it may concern:

Be it known that we, SAMUEL E. BARTLETT and HENRY E. WAITE, of New York city, county of New York, State of New York, have invented new and useful Improvements in Transmitters for Telephones, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, making part of this specification, in which I Figure 1 is a bottom view of a cork floor with the microphone applied. Fig.2 is a ver tical section through the cork'floor shown in Fig. 1 and its supporting-stand; and Fig.3 is a similar view, showing a modification in the form ofthe parts; and Figs. 4 and 5show modifications in the form of the microphone.

Ourinvention relates to a novel'arrangement of the microphone in connection with its supports, whereby the action of the soundwaves upon the floor upholding the microphone is more fully utilized and rendered available for the transmission of articulate sound; and it eonsistsin applying the microphone-to the un der side of a floor of cork or equivalent soundabsorbentand non-resonant material upheld by a stand orsupport in such a manner astoleave it unbound or loose therein, while at the same I time guarding it against accidental displacement, thereby securing under advantageous conditions and as fully as practicable the results of molecular disturbance in said floor.

It further relates to a novel construction of the microphone, and-to a novel arrangement of its parts, as hereinafter explained.

In the accompanying drawings, A represents a stand or support, made preferablyin the form of a shallow hollow cylinder or ring, and of any suitable material; but it may,ifdesired, be made in rectangular or'other suitable form. This stand or ring has a groove, to, in its inner face, formed between two annular flanges, a t and a, made either in one piece with the stand, as shown in Fig.2, or, if pret'erred,one of them may be made in the form of a removable ring, as shown in Fig. 3, for facilitating the insertion or removal'of the floor B, said ring being sccured in place by screws or in any other suitable manner. There the flanges are formed on the stand, one of them, and by preference (No model.)

l the upper one, a, should be of less width than the other, so that the cork floor-or support may be pressed by it into the retaining-groove a.

The floorB is made of cork or an eqnivaent sound-absorbent and non-resonantmaterial, of a width or diameter somewhat less than the diameter of the annular groove a, in which it rests, and of a thickness somewhat less than the width of said groove between the walls or flanges a and M, as shown, so as to leave the floor or piece of cork unbound or not in any way clamped, and onlyheld against accidental displacementi'rom thestandorsnpport A. This is important, as it has been found that when the cork is held lightly and lliilZl-ttllillltlttl the best results of molecu ar a tion or disturbance in the floor due to the action ot'the sonndaraves thereon are secured. r

The plate B is shown in Fig. 3 with an annular rabbet or shoulder, which permits it to lie partly within the lower flange or side, (t of the retaining groove for preventing unnecessary side or lateral movement. To the lower sideof the floor or piece of cork thus supported themicrophonc is secured, made, by preterence,

in the form shown in Fig 1 and 2, though other forms may be used.

In Figs. 1 and 2 the microphone is .\llO\Vl] as consisting ofa central hub or cylinder, 0, of carbon or other suitable conducting material, provided with a series of cylindrical sockets,

in which tenonson theJnner endsot'anumherot' radially-arranged cylinders, 0, test, the outer ends or tenons of said cylinders being support.-

ed in separate blocks or cylinders (J C, 850., as shown. The blocks, hubs, or cylinders O (J C are shown perforated and secured to the cork diaphragm by screws (Z 6; but they may be Secured thereto in any other suitable manner, and the ends of the cylinders G or of the 0 tenons thereon rest lightly in the sockets in said blocks or hubs G and 01-0 it will be seen that the inner ends of all the radial pieces or cylinders rest in the central hub, O. Onehalf of the number (eight being shown) have 5 their outer supporting-blocks, G (J 0 U all connected by a suitable conductor, 0, with each other and with one wire, f, of the telephone-' line, the others, 0 being similarly connected with each other and with the other wire,f, of I00 the line or with the battery and ground. In this arrangement it will be seen that the central hub and any one or more of the radiating spokes or cylinders and their supports forming a connection between the wires f and f will answer as the electrodes of a microphone complete in itself, so that if from any cause any one or more of the spokes of each half C or G should become inoperative the others, through the connections described, will continue to act. and the operation of thetransmitterwill not be materially affected.

In Fig. 3 the arrangement of the parts ts substantially the same as that shown in Figs. 1 and 2; but in thistheradialcylindersaremade hollow and are mounted upon radial rods {1, restingin the sockets in the hubs U and (J or In this construction the cylinders may be made in two or more short sections or rings strung on the rods or spindles 9, like beads or washers, thereby giving increased multiple contact.

In Fig. at the microphone is shown as composed of longitudinal strips or bars H and H, provided with screw s for securing them to the lower surface of the cork, said bars having notches or sockets cut in their upper edges at h for the reception of a ntnnber of transverse condur tors, l, the surfaces in contact. being by preference provided with corrugations or ribs, as shown, with the ribs on the transverse bars crossing those on the longitudinal bars; and in Fig. 5 the transverse bars I are shown made in cylindrical form, wi h journals resting in bearing-sockets in thelongitudiual bars H and B, one of which connects with one wire, f, and the other with the other wire, f, of the line. In these as in the arrangement first above describrd any one of the transverse bars I or 1, like the radial bars described, serves to connect the electrodes, so that if trom any cause one or more should cease to act the connection will still be complete, and the microphone will continue to operate through the others. Thus the form of the microphone or of the parts thereof may be .varied; but,we prefer to give it a multiple form, substantially such as described, whereby if any one of the several microphones should cease to act the action of the device as a whole will not be interfered with or materially impaired. The sound-waves act upon the upper surface of the cork B, being absorbed, and are conveyed by molecular action therein to the microphone secured to its lower surface, as described-an arrangementwhich, in connection with the manner of supporting said cork, as described, has been found in practice to constitute a telephonic transmitter of unusual power and eflectiveness.

In telephone-transmitters as ordinarilyconstructed a diaphragm is employed held grasped at its edges and under a certain degree of ten sion, dependence being placed upon its mechanical disturbance or vibration under the action of the sound-waves for the desired results, while in our arrangement of the cork floor supporting the microphone, whereby it is left untrammeled, we do away with thcmechanical vibration referred to and rely solely upon molecular disturbance produced in the cork by the action of the sound-waves impinging upon its surface.

The parts of the microphone are by preference of carbon; but. other suitable conducting material may be used in lieu thereof.

Having now described our invention, we claim as new 1. In a transmitter for telephones, a cork tloor upheld loosely in its supporting-stand, substantially as described, whereby it is left untrammeled and free to vibrate therein, in combination with a microphone suspended from its lower face and receiving its disturbances through molecular action in the cork resulting from the action of the sound-waves impinging upon its surface.

2. The microphone consisting of a central hub, bars or rods radiating therefrom, hollow rings or cylinders mounted thereon, and outer supports for said spokes or rods, connected with each other and with the line-wires, sub stantially as described.

In testimony whereof we have hereunto set our hands this 21st day of November, A. I). 1881.

SAMUEL lI. BARTLE' I. HENRY E. WAlTE. \Vitnesses:

(J. H. HANKINSON, ALONZO S. Evans. 

